There are two classes of mesh-type atomisers: vibrating mesh and static mesh.
The vibrating mesh atomisers of interest are disclosed in, for example, U.S. Pat. Nos. 4,533,082 and 5,152,456. They produce a stream of liquid droplets by vibrating a perforate membrane (mesh) having its inner face in contact with liquid so that droplets are expelled from holes in the membrane at each cycle of vibration. The size of droplets produced depends on the holes' size. The membrane is activated by a vibrating means connected to the housing of the device. Atomisers of this type require the means to deliver liquid to the mesh and include an additional device for vibrating the mesh. These vibrating mesh atomisers have problems with clogging and disinfection.
Static mesh nebulizers apply a force on the liquid to push it through a static mesh. In early models the liquid was supply by means of a pressure pump or the like. The U.S. Pat. No. 6,651,650 described this type of atomiser. The device has ultrasonic nebulisation mechanism including piezoelectric element, a step horn and a mesh. The bottom part of the step horn is in contact with the liquid to be atomized. This liquid is delivered to the mesh through the hole in the step horn, which functions as an ultrasonic pump. The liquid to be atomized is emitted out of the holes in the mesh toward the aerosol-emitting outlet. The mesh deterioration due to clogging, e.g. by suspension particles, is a cause of concern for both vibrating and static mesh atomisers. Other problems with this prior art include: low delivery rate and limited volume, which restricts this technology mainly to the medical applications. The majority of mesh-type atomisers require supply mechanisms to deliver liquid from container to the mesh. Also, all mesh-type atomisers pose significant difficulties with cleaning and disinfection.